Many battery-operated portable communications devices, such as wireless telephones, personal data assistants, and wireless pagers, include a RF power amplifier which facilitates communication over a wireless network. The communication protocol implemented by the wireless network usually requires the communication device to adjust the RF power output of the amplifier in accordance with a variety of characteristics, including maximum/minimum signal power thresholds and power control level commands transmitted by the network.
To facilitate required adjustments in RF output power, typically the communications device includes a DC/DC converter that is connected to the battery and the power amplifier. Based on the network power threshold/level commands, the DC/DC converter adjusts the RF output power by varying the DC bias that is applied to the power amplifier. However, the conversion from battery voltage to amplifier bias voltage is inefficient. As a result, much of the available battery capacity is not converted to useful work but is, instead, wasted as heat.